System and method for delivering energy to tissue

An ablation system for treating atrial fibrillation in a patient comprises an elongate shaft having proximal and distal ends, a lumen therebetween and a housing adjacent the distal end of the elongate shaft. An energy source is coupled to the housing and is adapted to deliver energy to a target tissue so as to create a zone of ablation in the target tissue that blocks abnormal electrical activity thereby reducing or eliminating the atrial fibrillation in the patient. A sensor is adjacent the energy source and adapted to detect relative position of the energy source to the target tissue or characteristics of the target tissue. The system also has a reflecting element operably coupled with the energy source and adapted to redirect energy emitted from the energy source in a desired direction or pattern.